Technical Field
The present disclosure pertains to internal combustion engines having a reciprocating piston slidably mounted within a cylinder and, more particularly, to a compression ring adapted to provide a seal between a top surface of the piston and a wall of the cylinder.
Description of the Related Art
Today's most common internal combustion engines are equipped with a cylinder, a piston slidably mounted in the cylinder, and a cylinder head mounted on the cylinder that in combination define a combustion chamber. Such engines are operated with a variety of fuels, including gasoline, diesel, biodiesel, hydrogen, ethanol alcohol (ethyl alcohol), propane, natural gas and others. In the past few years, new technologies have emerged, some in development and some already on the market, in which water, water injection, and other similar liquids are utilized.
In most internal combustion engines employing a piston-cylinder arrangement, the piston is slightly smaller in outside diameter than the inside diameter of the cylinder bore. At least one and usually three rings are used around the circumference of the piston to provide a seal between the piston and the wall of the cylinder. These rings are used in different configurations and are typically made from spring metal.
Most liquid type fuels are fed to the combustion chamber using a carburetor, port fuel injection or direct injection. The liquid fuel is converted to a mist or a spray during its transition to the combustion chamber. Once such spray touches a surface of the combustion chamber, it is turned back to a liquid. One such surface is the cylinder walls. This conversion back to liquid form inhibits complete consumption and burning of the fuel.
In current technologies during compression cycles the top ring is collecting liquid fuel from the cylinder walls, and it becomes trapped in the volume between the piston and cylinder. It is most critical during the compression stroke of a 4-stroke engine, where the pressure is high enough that once the piston reaches top dead center, the combustion creates maximum pressure to push the piston away from the cylinder head. This pressure pushes some of the liquid collected from between the piston and the cylinder wall past the piston and into the oil pan area. This is known as “blow-by.” In a water-based fuel system and in hydrogen-based fuels where the by-product of the combustion is mostly water, such blow-by liquids are mixed with the engine oil residing in the oil pan below the piston.
Piston reciprocation occurs more than 1000 times per minute even at low rpm. In a multiple cylinder engine the amount of blow-by is substantial. The blow-by results in wasted fuel and contamination of the oil, creating a milky type substance that can cause rapid wear of internal parts of the engine and premature failure.
Although the space between the piston cylinder wall and top ring is very small, it can accumulate trapped liquid to a large volume very rapidly. Attempts have been made in the past, with some success, to reduce blow-by by using multiple rings in a variety of shapes and configurations on the piston. None, however, appear to have addressed eliminating or preventing the accumulation of liquid in this space between the piston cylinder wall and the top ring.
Shown in FIG. 1 is a cross-sectional view of an assembly 20 having a piston 22 slidably mounted within a cylinder 24 that is covered with a cylinder head 26 to define a combustion chamber 28. The piston 22 is mounted to a connecting rod 30 that in turn is coupled to a crankshaft 32, which is configured to move the piston 22 in a reciprocating fashion up and down in the cylinder 24. The construction and operation of the crankshaft 32 and connecting rod 30 will not be described in detail herein inasmuch as these are well-known elements to those of skill in the art. Similarly, the cylinder head 26 includes a pair of valves 34, a spark plug 36, and a fuel injector 38 that are in communication with the combustion chamber 28 in a well-known manner. These elements will also not be described in detail herein inasmuch as they form the environment within which the invention is designed to function, and such elements are well known to those of skill in the art.
Turning next to FIG. 2, shown therein in greater detail is a partial enlarged view of the assembly 20 of FIG. 1 showing a top ring 40 mounted within a channel 42 formed in a sidewall 44 of the piston 22. As is well known, the piston 22 has a cylindrical exterior sidewall surface 44 that is slightly smaller in diameter than an exterior sidewall surface 46 of the cylinder 24. The top ring 40, generally known as a compression ring, extends outward from the exterior sidewall surface 44 of the piston 22 to ride up against the interior cylinder wall 46 in a fashion that scrapes liquid 48 off the cylinder wall 46 and reduces blow-by from the combustion chamber 28 to a crankcase area around the connecting rod 30 and crankshaft 32 below the piston 22.
More particularly, during a typical four-stroke combustion cycle, fuel is injected into the combustion chamber 28 via the fuel injector 38. This fuel is shown as a spray 50 in FIG. 1. The spray of liquid fuel 50 can accumulate on the cylinder wall 46 in the form of droplets 48 shown in FIG. 2. During the movement of the piston 22 in a reciprocating fashion within the cylinder 24, the top ring 40 will scrape and collect the droplets 48 in the space 52 between the piston 22 and the cylinder 24. The liquid accumulates as indicated by reference number 54 within the space 52. Under the pressure of combustion, this trapped liquid 54 can blow past the top ring 40 and be injected into the crankcase containing the crankshaft 32, connecting rod 30, and lubricating oil.
Hence, there is a need to eliminate this trapped liquid 54 in the space 52 between the piston 22 and cylinder wall 24 to reduce the potential for damage to the engine, and to increase engine performance.